// ========================================================================
// Copyright (c) 2004-2009 Mort Bay Consulting Pty. Ltd.
// ------------------------------------------------------------------------
// All rights reserved. This program and the accompanying materials
// are made available under the terms of the Eclipse Public License v1.0
// and Apache License v2.0 which accompanies this distribution.
// The Eclipse Public License is available at 
// http://www.eclipse.org/legal/epl-v10.html
// The Apache License v2.0 is available at
// http://www.opensource.org/licenses/apache2.0.php
// You may elect to redistribute this code under either of these licenses. 
// ========================================================================

package org.eclipse.jetty.server.handler;

import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.eclipse.jetty.server.Handler;
import org.eclipse.jetty.server.Request;
import org.eclipse.jetty.server.Server;

/* ------------------------------------------------------------ */
/**
 * A <code>HandlerContainer</code> that allows a hot swap of a wrapped handler.
 */
@SuppressWarnings({ "unchecked", "rawtypes" })
public class HotSwapHandler extends AbstractHandlerContainer
{

	private volatile Handler _handler;

	/* ------------------------------------------------------------ */
	/**
     * 
     */
	public HotSwapHandler()
	{}

	/* ------------------------------------------------------------ */
	/**
	 * @return Returns the handlers.
	 */
	public Handler getHandler()
	{
		return _handler;
	}

	/* ------------------------------------------------------------ */
	/**
	 * @return Returns the handlers.
	 */
	public Handler[] getHandlers()
	{
		return new Handler[] { _handler };
	}

	/* ------------------------------------------------------------ */
	/**
	 * @param handler Set the {@link Handler} which should be wrapped.
	 */
	public void setHandler(Handler handler)
	{
		try
		{
			Handler old_handler = _handler;
			_handler = handler;
			if (handler != null)
			{
				handler.setServer(getServer());
				if (isStarted())
					handler.start();
			}

			if (getServer() != null)
				getServer().getContainer().update(this, old_handler, handler, "handler");

			// if there is an old handler and it was started, stop it
			if (old_handler != null && isStarted())
			{
				old_handler.stop();
			}

		} catch (RuntimeException e)
		{
			throw e;
		} catch (Exception e)
		{
			throw new RuntimeException(e);
		}
	}

	/* ------------------------------------------------------------ */
	/* 
	 * @see org.eclipse.thread.AbstractLifeCycle#doStart()
	 */
	@Override
	protected void doStart() throws Exception
	{
		if (_handler != null)
			_handler.start();
		super.doStart();
	}

	/* ------------------------------------------------------------ */
	/* 
	 * @see org.eclipse.thread.AbstractLifeCycle#doStop()
	 */
	@Override
	protected void doStop() throws Exception
	{
		super.doStop();
		if (_handler != null)
			_handler.stop();
	}

	/* ------------------------------------------------------------ */
	/* 
	 * @see org.eclipse.jetty.server.server.EventHandler#handle(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse)
	 */
	public void handle(String target, Request baseRequest, HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException
	{
		if (_handler != null && isStarted())
		{
			_handler.handle(target, baseRequest, request, response);
		}
	}

	/* ------------------------------------------------------------ */
	@Override
	public void setServer(Server server)
	{
		Server old_server = getServer();
		if (server == old_server)
			return;

		if (isRunning())
			throw new IllegalStateException(RUNNING);

		super.setServer(server);

		Handler h = getHandler();
		if (h != null)
			h.setServer(server);

		if (server != null && server != old_server)
			server.getContainer().update(this, null, _handler, "handler");
	}

	/* ------------------------------------------------------------ */
	@Override
	protected Object expandChildren(Object list, Class byClass)
	{
		return expandHandler(_handler, list, byClass);
	}

	/* ------------------------------------------------------------ */
	@Override
	public void destroy()
	{
		if (!isStopped())
			throw new IllegalStateException("!STOPPED");
		Handler child = getHandler();
		if (child != null)
		{
			setHandler(null);
			child.destroy();
		}
		super.destroy();
	}
}
